In a Long Term Evolution (LTE) downlink system, a transmission time interval (TTI) includes a control region and a data region. The control region is mainly used to transmit control information by using a channel such as a physical downlink control channel (PDCCH). The data region is mainly used to transmit data information by using a channel such as a physical downlink shared channel (PDSCH). In addition, an enhanced physical downlink control channel (EPDCCH) may further be introduced in the data region as a supplement to and an enhancement of the PDCCH. In an LTE downlink transmission process, user equipment (UE) needs to demodulate downlink data on the PDSCH according to downlink information. An example in which the downlink information is a demodulation reference signal (DMRS) is used to describe a demodulation process. Generally, the process is specifically as follows: The UE first receives a DMRS sent by a base station, obtains a channel estimation result according to the DMRS, demodulates an EPDCCH by using the DMRS, so as to determine scheduling information of downlink control information (DCI), and demodulates downlink data on a PDSCH according to the DCI and the channel estimation result. If the UE can correctly demodulate the downlink data on the PDSCH, the UE feeds back an acknowledgement (ACK) to the base station; or if the UE cannot correctly demodulate the downlink data on the PDSCH, the UE feeds back a negative acknowledgement (NACK) to the base station.
A TTI in an existing LTE system is 1 ms. To achieve a shorter round trip time and a shorter data transmission delay, currently a scenario in which a length of the TTI is set shorter is proposed in an advanced solution of the LTE system. For example, the length of the TTI is set to 0.5 millisecond, a time length of one symbol, or the like. FIG. 1 is a general schematic diagram of a timeslot structure of one TTI in the prior art. As shown in FIG. 1, one TTI includes two timeslots (slot): a first timeslot slot 0 and a second timeslot slot 1. There are seven symbols per timeslot. According to a protocol specification in the prior art, a DMRS location is defined on the last two symbols of the slot 0 and the slot 1. In the existing LTE system with the TTI of 1 ms, the UE receives downlink information in an mth subframe, then demodulates downlink data, and sends acknowledgement information in an (m+4)th subframe by using an uplink channel. By analogy, if the TTI in the LTE system changes to a TTI whose time length is one timeslot, that is, one TTI includes only one timeslot, the UE receives downlink information in an nth timeslot, then demodulates downlink data, and sends acknowledgement information in an (n+4)th timeslot by using an uplink channel.
According to a demodulation method in the prior art, when duration of the TTI becomes shorter, the TTI may not include the last two symbols of the timeslot. Consequently, the UE cannot receive the downlink information within the TTI, resulting in a technical problem that the UE fails to complete subsequent demodulation of the downlink data.